The food and beverage packaging industry has long been known to provide some indicating means to warn purchasers when the vacuum condition under which the food or beverage was packaged has been lost by failure of the closure seal. Such means may be a "pop top" closure of the type generally shown in U.S. Pat. No. 3,152,711 or in Patent No. 3,160,302. Patent No. 2,040,798 disclosed a tell-tale closure device for Mason jars or similar type containers which would indicate to a person whether or not the contents of the jars had been properly sealed during the "canning" process. The device would also indicate when the seal has been lost during storage of the processed products even though properly made initially during the "canning" process. Of course, the "pop top" closures and the Mason jar closure, in responding to loss of vacuum in the closed containers, would also indicate when that loss resulted from tampering, although that was not the principal purpose of the disclosures.
Another early closure arrangement is disclosed in Patent No. 2,880,900. Here a closure having an elastic inner diaphragm that, when the closure is applied to a product filled bottle in a vacuum packaging machine, distends inwardly to hold the contents of the bottle in place is disclosed. The arrangement is intended as a substitute for the cotton or crumpled paper dunnage that would otherwise be used to hold loose articles in place in a closed bottle.
A closure arrangement that is specifically intended as a tamper evident container is disclosed in Patent No. 4,519,515. Here, a disk seated atop the open neck of the container is coated at its top surface with microcapsules filled with a dye which changes color upon exposure to air. The capsules are ruptured, and the dye exposed to air, by the abrasive underside of the container cap when the cap is rotated to remove it from the container.
More recently, malicious tampering of product containers, especially containers of pharmaceutical products of the type such as headache and cold remedies normally displayed on store shelves has resulted in the disclosure of more elaborate tamper proof or tamper evident packages. Such tampering with hypodermic needles is a particularly insidious problem. For example, Patent No. 4,449,632 discloses a first container into which the product is placed, a second larger flexible container completely enclosing the first container but with a space between the two containers. The space between the two containers is filled with pressurized gas (or air) and an elastic layer or member is tightly stretched around the second container. If the package is violated as by a hypodermic needle penetrating both containers, or even just the second outer container, the pressurized gas is released and the elastic layer or member immediately squeezes the second container into contact with the first container. It is, for all intents and purposes, impossible for the person who violated the package to restore it to its initial condition. Thus, the collapsed second container provides a readily visible indication that the package has been tempered with. However, it is believed that the package is rather costly to manufacture and that it does not lend itself to convenient stacking and display on store shelves.